A bolus intravenous injecton of endotoxin (E), a major component of the cell wall of gram negative bacteria, results in acute renal failure (ARF). E-ARF may develop in rats without changes in systemic hemodynamics and is associated with peritubular and glomerular capillary injury. The proposal aims at characterizing the pathophysiology of E action in the kidney. The hypothesis is that E-ARF stems from a primary injury to renal endothelia. To test the hypothesis, a goal is to develop glomerular endothelial cell monolayers in culture. The effects of E will be studied in whole kidneys in vivo, in isolated kidneys perfused in-vitro and in renal endothelial cells grown as monolayers. 1) In whole kidneys exposed to E, studies will correlate renal function (glomerular filtration rate, renal blood flow and water and solute excretion) and morphology (light and electron microscopy) in intact rats and in rats made tolerant to E. The contribution of potential mediators of E-ARF will be assessed with inhibitors or antagonists of specific metabolic pathways. Particular emphasis will be directed at platelet activating factor (PAF); 2) To eliminate the contribution of cellular and humoral elements of circulating blood, functional and morphologic studies will evaluate the effects of endotoxin in isolated kidneys perfused in-vitro with a cell-free perfusate in the absence and in the presence of serum. The effects of PAF with and without specific antagonists will be evaluated. Kidneys from intact rats and from E-tolerant rats will be used; 3) To evaluate the effect of E on the renal vasculature, endothelial cell monolayers will be developed from rodent, bovine and primate renal arteries and glomerular capillaries using traditional methods and newer approaches of mechanical harvest, monoclonal antibodies and microcarriers for scale-up culture. Endothelial cell monolayers will be characterized morphologically and functionally. The effects of endotoxin on the structure, surface function, permeability, metabolic properties, phagocytosis and growth characteristics of these monolayers will be directly assessed. This multidisciplinary approach should facilitate interpretation of the data, yield an integrated understanding of the pathophysiology of E-ARF and suggest directions and rational means for possible prevention and therapy of E-ARF. The work with glomerular endothelial cell monolayer will explore new territories and open to investigation a glomerular cell type which remains poorly characterized to date.